<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <script>
        let hd = 3;
        let arr = [1,2,3];
        let obj = {}
        let str = "a";
        console.log(typeof str);
        console.log(typeof hd);
        console.log(arr instanceof Array); // true
        console.log(obj instanceof Object); // true

        function User(){

        }
        let zh = new User();
        class Personal{

        }
        let p = new Personal();
        console.log(zh instanceof Object); // true
        console.log(p instanceof Object); // true
    </script>
</body>
</html>